It has been observed that more than 90 tropical cyclones occur annually and an average life cycle of a cyclone is nine days. The top four countries with a maximum number of tropical cyclones are China, the Philippines, Japan and Mexico. These cyclones cause a lot of destruction every year in the coastal states. In this article, we will talk about tropical cyclones. We will learn what are tropical cyclones, their various features and especially tropical cyclone locations and its pattern. This topic is essential whenever you are studying Geography, especially oceanography and Disaster Management because it is very important to study this disaster so that proper management can be done by the coastal regions.
The word cyclone is derived from the Greek word which means coil of the snake. Because of such appearance in the Bay of Bengal as well as in an Arabian sea, this term i.e. cyclone was coined by Henry Peddington. Cyclones are the phenomenon that occurs in a low-pressure area where the rapid inward circulation of the air is seen and this air circulated in the anti-clockwise direction and the clockwise direction in the Northern Hemisphere and Southern Hemisphere respectively. These are also accompanied by storms as well as bad weather conditions. These are generally divided into two categories ie. Tropical cyclone and Temperate cyclone which is also known as Extra-Tropical Cyclone. The former occurs in between the tropics whereas the latter occurs in the temperate areas.
The cyclones that occur in the regions of Tropic of Cancer, as well as Tropic of Capricorn, are termed Tropical Cyclones which is a warm-season phenomenon and usually ranges up to 30° from the equator. These are also accompanied by the storms over the oceans which affects the coastal regions to a large extent and cause a lot of destruction as well with heavy rainfall, strong winds and storms etc. These are one of the most destructive natural disasters that occur in the warm ocean waters of tropical regions.
Some of the Most Important Characteristics of Tropical Cyclones are Given below:
It requires few conditions which help in the formation of these cyclones such as large sea surface, the temperature of more than 27°C, Coriolis force, variations in the wind speed, low-pressure area, etc. All these conditions lead to the formation of tropical cyclones.
It occurs in the tropical regions mostly 5° to 30° from the equator and it moves towards the poles where it starts weakening and then dies.
A typical tropical cyclone can move up to 300 - 400 miles per day whereas around 3,000 miles before it actually dies.
In terms of tropical cyclones, the Pacific Ocean ranks first whereas the Indian Ocean ranks second and the Atlantic Ocean ranks third. It does not occur in the other two oceans which are the Arctic and Southern ocean.
In the Southern Pacific ocean, where the phenomenon of LA Nina we came to see sometimes also lead to the occurrence of tropical cyclones which depends upon the various geographical locations and time.
These are considered as the most disastrous cyclones which run with an average speed of 120 kmph but sometimes it varies as well and can reach up to 200 kmph or sometimes even more. These cyclones with so much speed cause a lot of destruction in the coastal areas.
These cyclones only occur at a specific period of the year and during some seasons which are generally warm and under the trade winds influence, they generally move in the direction of East to West.
If we talk about the structure of the tropical cyclones, they have a sharp pressure gradient as they have closed isobars and these lead to a greater velocity of storms and in the centre, they have a low-pressure area that attracts winds from the surrounding areas.
Tropical cyclone locations generally include all the major oceans except the Southern and Arctic ocean. It affects the coastal regions of the Pacific or Mexico, South East Asia, North-East Australia as well as islands present in the South Pacific and other regions etc.
They are given different names every year according to the list prepared by the international body i.e World Meteorological Organisation and any name can only be repeated after six years.
Location and Patterns of Tropical Cyclones
[Image will be Uploaded Soon]
Various characteristics determine the occurrence of tropical cyclones in the region which we have talked about above. The geographical conditions lead to the occurrence of the cyclones. As we can see on the map, the Tropical cyclone locations are near to the tropics. The most important regions where tropical cyclones usually occur along with the less prominent regions are given below in the table as well as the various names of the tropical cyclones as according to the different regions are also represented in the table:
The oceans in the Tropical regions leads to having 80 tropical storms annually among which generally ⅔ are considered as severe. If we talk about the ranges where they occur, usually around 90% occurs up to 20°N and 20°S from the equator. The maximum number of cyclones can be seen in the Pacific Ocean and after this in the Indian Ocean and then in the Atlantic Ocean can be seen.
These tropical cyclones are the phenomenon that is related to the warm season and the highest frequency is after the time when the earth receives maximum insolation i.e on June 21 in the Northern Hemisphere and December 22 in the case of the Southern Hemisphere. The water reaches its maximum temperature after a few weeks and thus most of the tropical cyclones occur during the time of late summers or early autumn seasons. In the Northern hemisphere, these occur from July to September whereas, in the Southern Hemisphere, these cyclones occur during the period of January to March.
Favourable conditions of the wind systems also play an important role in the formation of the cyclones. That's why it is said that lower latitudes are more favourable for the occurrence of tropical cyclones due to the atmospheric circulation in the region. For example, in the Atlantic Ocean and North East Pacific ocean, cyclones occur with easterly waves which intensify as well as contract the horizontal phenomenon that leads to or formation of cyclones. If we talk about the Western Pacific Ocean, here you can see TUTTs which means Tropical Upper Tropospheric Troughs that helps in the formation of these cyclones. Besides, these sometimes external geographical factors also lead to the development of cyclones such as modification of the easterlies by the mountains present in Central America or Mexico towards the Caribbean and East Pacific.
In both the Hemispheres, cyclones used to move in western motion and towards the poles. Trade winds play a vital role in the movement of tropical cyclones in western motion whereas if we talk about the movement towards the poles, two factors are considered as responsible which are subtropical highs and Coriolis force. These two factors play a vital role in the deflection of the cyclones towards the poles. When the motion is about to change towards the eastern side, it is known as recurve whereas the cyclones move much far in the Northern Hemisphere than the southern hemisphere because of the presence of warm currents in the upper hemisphere. After some time they weaken as they move towards the poles.
Therefore, to sum up we can say that tropical cyclones are the phenomenon that occurs in the presence of certain conditions such as the temperature of more than 27°C and having low pressure and various other conditions that lead to its occurrence. They are generally found in the tropical and subtropical regions on the ocean surface but do affect the continents as well. Only two oceans are there where these cyclones do not occur but at other places, sometimes these cyclones lead to violent storms and activities which can be disastrous as well. For these violent natural calamities, proper disaster management is required by the coastal regions present in the tropical cyclones range.